This research is designed to determine neuroanatomical and neurochemical correlates of addictive and aggressive/impulsive behavior in human subjects. The principal focus of these studies is the measurement and correlation of regional cerebral glucose metabolic activity, using positron emission tomography (PET), brain volumes using magnetic resonance imaging (MRI), cerebrospinal fluid metabolites, and measures of impulsive/aggressive behavior and excessive alcohol consumption. We collected full, volumetric T-1 weighted MR images using a 1.5 T scanner to measure intracranial volumes in 140 alcoholics (89 males and 51 females) and 104 healthy, non-alcoholic comparison subjects (53 males and 51 females). An automated segmentation program was used to divide the intracranial contents into CSF, gray and white matter (Human Brain Mapping, 5:194-205, 1997). When we measure brain volume we are measuring the combined effect of two processes: growth and degeneration. Growth determines maximum brain size achieved during life. Maximal brain growth can be estimated by intracranial volume (ICV) and since ICV remains constant throughout life, brain degeneration can be measured by the ratio of cerebral volume or gray matter or white matter volume to the remainder of the intracranial contents. Alcoholics show greater brain degeneration than non-alcoholics. Women appear to be more affected than men. Alcoholics also show significantly greater brain shrinkage than controls by their mid to late twenties. In addition, alcoholics have smaller intracranial volumes than controls. However, this difference is small and barely reaches statistical significance, and brain degeneration accounts for a greater amount of the difference in brain volume between alcoholics and controls than brain growth does. Neither estimated lifetime alcohol consumption nor number of years of heavy alcohol use predict brain degeneration among alcoholics. Similarly, presence or absence of co-morbid psychiatric disorder or other substance abuse does not affect brain shrinkage among alcoholics.